DESCRIPTION: Breast cancer treatment is the leading cause of lymphedema in the United States. Two million women with breast cancer are at risk to develop lymphedema during their lifetimes. Imprecise measurement of lymphedema is a major deterrent to rigorous research on risk factors associated with the development of lymphedema and treatment efficacy. This study proposes to evaluate and compare two state of the art measures of limb volume compared to a "gold standard" measure in 40 women with lymphedema following breast cancer treatment. The primary specific aim is to assess the reliability, validity, sensitivity, and practicality of two measures of limb volume (sequential circumferential limb measurement and infrared laser measurement with the perometer) compared to water displacement as the "gold standard" measure. A secondary aim is to assess and compare physiological parameters (tissue oxygenation and skin temperature) in affected and non-affected arms. These aims will be accomplished through laboratory assessments (sequential limb circumferences, perometry, and water displacement) at two points in time with a 4-hour interval on the same day for each subject. The two measurements at different points in time are designed to assess and compare the sensitivity of the 3 modalities to capture changes in limb volume over time. Findings will guide the selection of a reliable, valid, sensitive, and practical measurement protocol for nursing assessment of mild to severe lymphedema and changes over time. Successful completion of this work will lay the foundation for a nursing study aimed at 1) testing the effectiveness of targeted interventions to prevent, control, or resolve lymphedema secondary to breast cancer treatment, and 2) testing the effectiveness of interventions to achieve other associated outcomes that are important for the quality of life of women with breast cancer.